A labour shortage, rapid urban population growth and rising social tension were to blame for the spate of recent violence against police in Xi'an, officers said Tuesday.

There had been at least 13 cases of violence against police in Xi'an since April, and May saw six attacks within a week. The problems have even caught the attention of the Ministry of Public Security. Zhou Yong Kong, ministry chief issued a memo calling for officers to be better equipped.

He Jie, a spokesman for the Public Security Bureau in Xi'an, said the force was understaffed.

"Our police force can not keep up with population growth in Xi'an, although we have expanded our team form 8,000 in 1996 to 12,000 this year," said Hu.

Hu said Xi'an's population has risen sharply due to the arrival of a large number of migrant farmers from the countryside.

Zhang Wei, director of the Legal Affairs department at the Xi'an Public Security Bureau, said the manpower shortage was the force's biggest challenge. "When people are frustrated or people believe their interests have been hurt, they often blame the police," he was quoted as saying in the Sanqin Daily Tuesday.

"It should be pointed out that Xi'an is developing rapidly and the society is changing fast, "he said.

More than 3,000 policemen were injured or killed while on the job in the first half of the year, according to a report by the Beijing Daily in August.

(Shenzhen Daily September 22, 2005)